1. Field of the Invention
The present invention relates to the use of at least one amine oxidase inhibitor for modulating the activity of the lysine-specific demethylase (LSD1) in a mammal or for the manufacture of a medicament for modulating the activity of the lysine-specific demethylase (LSD1) in a mammal. The invention also relates to a pharmaceutical composition for controlling the androgen receptor-dependent gene expression, comprising an effective dose of at least one amine oxidase inhibitor suitable for modulating the activity of the lysine-specific demethylase (LSD1) in a mammal. The invention also relates to a method for controlling the androgen receptor-dependent gene expression in a mammal, said process comprising the step of administering to said mammal, on a suitable route, an effective dose of a pharmaceutical composition modulating an activity of the lysine-specific demethylase (LSD1) in a mammal. Finally, the invention also relates to assay systems allowing to test LSD1 modulators for their ability to modulate, preferably inhibit, LSD1 function.
2. Discussion of Background Information
The androgen receptor (AR) is a member of the steroid hormone receptor family of transcription factors which regulate diverse biological functions including cell growth and differentiation, development, homeostasis and various organ functions in a mammal, particularly in a human. By binding suitable ligands like androgens to the ligand binding domain, functions of the AR are activated which are essential for the differentiation, development and maintenance of male or female reproductive organs and non-reproductive organs (as, for example, the prostate or the mammae).
Transcriptional regulation by nuclear receptors such as the androgen receptor (AR) involves interaction with multiple factors that act in both a sequential and combinatorial manner to reorganize chromatin1. Central to this dynamic reorganization is the modification of core histones. The N-terminal tails of histones are subject to various covalent modifications such as acetylation, phosphoryl-ation, ubiquitination and methylation by specific chromatin-modifying enzymes2. Histone methylation at specific lysine residues is linked to both transcriptional repression and activation2. When searching for new AR interacting proteins, Lysine specific demethylase 1 (LSD1)3 was found to be one example of the chromatin-modifying enzymes.
LSD1 contains a centrally located swirm domain which functions as a putative protein-protein interaction motif, and also contains a C-terminal amine oxidase (AO) domain that harbours the demethylase activity3 (FIG. 1b). Endogenous LSD1 and AR associate in vivo in androgen-sensitive tissues such as testis (FIG. 1a). To map the interaction domain between LSD1 and AR in vitro, GST pull-down analyses with labelled LSD1 and mutants thereof together with GST-AR fusion proteins were performed. As shown in FIG. 1b, full-length LSD1, as well as the swirm domain (LSD1 175-246) and the AO domain (LSD1 247-852) associate with either the N-terminus (NTD), the DNA binding domain (DBD), or the ligand-binding domain (LBD) of AR. In contrast, neither the N-terminus of LSD1 (LSD1 1-174) nor the GST control interact with AR.
It was now surprisingly found that the demethylating enzyme LSD1 is expressed ubiquitously in human and murine fetal and adult tissues (FIG. 2a and data not shown). Furthermore, it was also detected that LSD1 is found in the same cells (and in the same sub-cellular areas) where the AR is located (FIGS. 2c, d). In the course of the research resulting into the present invention, the above (and further) findings led to the conclusion that the demethylating enzyme LDS1 may exert a controlling influence on androgen-dependent gene expression. Furthermore, it was found that monoamine oxidase inhibitors as, for example pargyline, clorgyline or deprenyl (=selegiline) may be used to control demethylase activity and thereby regulate the AR. Thus, a specific modulation of LSD1 activity might by a promising therapeutic target in tissues where the AR plays a pivotal physiological role.